Magnetic stirrer apparatus

ABSTRACT

Magnetic stirrer apparatus is disclosed, wherein a shaft extends through the bore of a closure in sealing relation therewith, and a magnetic stirrer bar is rotatably coupled to the closure. In one form of the invention, the stirrer bar is pivoted on the shaft adjacent one end thereof. In another form, the shaft and stirrer bar are pivoted on the closure. Longitudinal adjustment of the shaft in the stopper provides adjustment of the apparatus for use in vessels of various sizes. In one form of the apparatus, the shaft and stirrer bar are wholly encapsulated in chemically inert plastic material, thereby avoiding contamination of stirred matter.

United States Patent [72] inventor [21 Appl. No. 22] Filed [45] Patented [73] Assignee [54] MAGNETIC STIRRER APPARATUS 5 Claims, 5 Drawing Figs.

[52] US. Cl 259/107 [51] int-Cl B01f7/16 [50] Field ofSearch 259/107, 108,102, 016.46, 7, 27. 11-15, 48-52, 59,70

[56] References Cited UNITED STATES PATENTS 2,622,943 12/1952 Wan Kat et a1. 259/107 X 2,837,326 6/1958 Baron 259/108 1,984,975 12/1934 Lodder 259/DiG. 46 2,630,303 3/1953 Krucker 259/108 2, 88,992 9 1954 Russo 259/107x 2,844,363 7/1958 Clark 259/10sx 2,859,020 11/1958 Eddyetal 259/D1G.46 2,958,517 11/1960 Harkeretal 259/D1G.46 2,932,493 4/1960 Jacobs 259/102 3,265,369 8/1966 Harrison 259/108 Primary Examiner.lordan Franklin Assislan! Examiner-Geo. V. Larkin Atlorney-Seidel, Gonda & Goldhammer ABSTRACT: Magnetic stirrer apparatus is disclosed, wherein a shaft extends through the bore of a closure in sealing relation therewith, and a magnetic stirrer bar is rotatably coupled to the closure. in one form of the invention, the stirrer bar is pivoted on the shaft adjacent one end thereof. in another form, the shaft and stirrer bar are pivoted on the closure. Longitudinal adjustment of the shaft in the stopper provides adjustment of the apparatus for use in vessels of various sizes. in one form of the apparatus, the shaft and stirrer bar are wholly encapsulated in chemically inert plastic material, thereby avoiding contamination of stirred matter.

MAGNETIC STIRRER APPARATUS This invention relates to magnetic stirrer apparatus, and more particularly, to magnetic stirrer apparatus for use in nonmagnetic vessels.

It has heretofore been recognized that the contents of a nonmagnetic vessel may be stirred by placing within the vessel a rotatable magnetic member, and placing outside the vessel, in juxtaposition to the internally placed magnetic member, a rotating magnet. Rotation of the externally placed magnet causes rotation of the internal magnetic member, and consequently, agitation of the contents of the vessel.

A practical apparatus of this sort is disclosed in US. Pat. No. 2,958,5 l7, assigned to the assignee of the present application. In such patent, the magnetic stirrer bar is received in a stirrer holder, the stirrer holder having a tapered lower end in engagement with a depression in the floor of the vessel. A rod coupled to the stirrer holder and to an opening in the closure of the vessel maintains the stirrer holder in an upright position, for rotation about a fixed axis.

The stirrer bar in the above-described patented apparatus rides at a fixed vertical position, and does not shift laterally during operation into contact with the vessel walls. Moreover, because its location with respect to the external drive magnet is constant, its speed of rotation is constant.

Substantially constant speed and relatively fixed agitator position are decided advantages in some stirrer applications.

Unconstrained magnetic stirrer bars and bars supported by universal swivels, both known prior art apparatus, do not have the above-mentioned advantages. On the other hand, they do have the advantage of usability in general purpose vessels and in vessels of any given height. The present apparatus is one which provides all of the advantages of a magnetic stirrer placed at a fixed vertical position in a vessel and at a fixed axial location; as well as the advantages of adaptability to use in conventional vessels, regardless of size.

For some applications, it is essential that a stirrer be chemically inert, so as not to contaminate the stirred material. For example, in tissue culture, it is important that the stirrer not impart to the stirred medium metallic trace ions. The structure of the present apparatus, in one operative form, obviates this hazard.

In view of the foregoing, it is an object of the present invention to provide a novel magnetic stirrer apparatus.

It is another object to provide a magnetic stirrer apparatus wherein a stirrer element is maintained at a fixed height within a vessel, for rotation about a fixed axis.

It is still another object of this invention to provide magnetic stirrer apparatus wherein the height of the stirrer within a vessel can be readily adjusted.

It is another object to provide magnetic stirrer apparatus suitable for use in conventional vessels.

It is yet another object to provide magnetic stirrer apparatus, particularly suited for use in tissue culture, wherein the possibility of contamination of the stirred medium by metallic trace ions is minimized.

It is yet another object to provide a magnetic stirrer wherein a stirrer bar is supported for rotation by a unique, low-friction pivot arrangement.

The foregoing and other objects are realized, in one presently preferred form, by an apparatus comprising a shaft adapted to pass through the bore of a stopper in gastight sealing relation therewith, so that the shaft may be selectively axially positioned within the bore; and a magnetic stirrer bar coupled to the shaft adjacent one of its ends for rotation about an axis defined by such shaft.

For the purpose of illustrating the invention, there is shown in the drawings a form which is presently preferred; it being understood, however, that this invention is not limited to the precise arrangements and instrumentalities shown.

FIG. 1 is a side elevation view, in cross section, showing apparatus in accordance with the present invention.

FIG. 2 is a cross-sectional view, showing details of the present apparatus.

FIG. 3 is a cross-sectional view, generally similar to FIG. 2, showing the various structural elements of the apparatus in disassembled form.

FIG. 4 is a cross-sectional view of a modified form of the apparatus.

FIG. 5 is a cross-sectional view showing details of another modified form of the apparatus.

Referring now to the drawings in detail, wherein like numerals indicate like elements, there is seen in FIG. 1, a form of magnetic stirrer apparatus designated generally by the reference numeral 10, operatively disposed within a vessel 12. The vessel 12, it should be understood, is of nonmagnetic material, such as glass, ceramic, or the like. The vessel 12 is of conventional construction, and is not, per se, a part of the present invention.

The illustrated vessel 12 includes a top opening 14 and a pouring spout 16. A closure member, in the form of an elastomeric stopper 18, is shown in gastight sealing relation with the top opening 14. A stopper 22 is shown in place in the pouring spout l6. Stopper 18 includes a central bore 20.

Magnetic stirrer apparatus 10 comprises an elongated vertically disposed shaft 24 extending through the central bore 20 of the stopper 18. Outer surfaces of the shaft 24 are in gastight sealing relation with the central bore 20. Rotatably coupled to a lower end of the shaft 24 is a rotor assembly, designated generally by the reference numeral 26.

Referring now to FIG. 2, the rotor assembly 26 comprises a bearing, designated generally by the numeral 27, an elongated sleeve member 28, and a stirrer bar 30 associated therewith. In the illustrated form, the sleeve member 28 in a hollow member including a major axially extending bore 32 and a minor axially extending bore 34, coaxial therewith The diameter of the minor bore 34 is slightly greater than the outer diameter of the shaft 24. Thus, the upper portion 29 of the sleeve member 28 is rotatably received on the shaft 24. The end portion may be formed integrally with shaft 24. An enlarged end portion 36 serves to retain the sleeve member 28 on the shaft 24. The diameter of the enlarged end portion 36 is slightly less than the diameter of the major bore 32, within which the enlarged end portion 36 is enclosed.

A shoulder 38, defined by the step between the major bore 32 and minor bore 34, provides a bearing surface that faces downwardly between the sleeve member 28 and the enlarged end portion 36 defines a bearing surface 37 that faces upwardly when the sleeve member 28 is in an operative position.

When the sleeve member 28 is in an operative position, a lower portion thereof extends axially beyond the end of the shaft 24. Such portion may be referred to for convenience as a skirt portion 40. A bore 42 extends through the skirt portion in a direction transverse to the axes of the bores 32 and 34 and the shaft 24. In its operative position, the stirrer bar 30 is received in the bore 42. The stirrer bar 30 may be press-fitted in the bore 42, thus obviating the need for fasteners or the like. As is apparent from FIG. 2, the presence of the stirrer bar 30 in the bore 42 causes the sleeve member 28 to be retained in association with the enlarged end portion 36 of the shafi 24. Upward movement of the sleeve member 28 with respect to the shaft 24, FIG. 2, is precluded by contact between the stirrer bar 30 and an end face of the end portion 36 of shaft 24.

Referring now to FIG. 3, the various elements of the rotor assembly 26 are seen in disassembled form. For the purpose of assembly, the sleeve member 28 may be placed over the upper end of the shaft 24, and slid downwardly until shoulder 38 contacts the enlarged end portion 36. The stirrer bar 30 may then be inserted into the bore 42 to complete the assembly.

The manner in which the present apparatus avoids con tamination of the stirred medium by metallic trace irons is apparent from the drawings. In the illustrated form of the invention, the shaft 24 includes a metallic core element 44 and a chemically inert plastic polymeric outer coating 46. The above-described enlarged end portion 36, in the illustrated form, is integral with the outer coating 46. It will be appreciated that the enlarged end portion 36 may, in some embodiments, take the form of a collar or cap, press-fitted over an end of the shaft 24. The outer coating 46, in a preferred form, is of the fluorinated or partially fluorinated and partially chlorinated hydrocarbon material sold under the trademark TEFLON by E. I. DuPont de Nemours Co. If the sleeve member 28 is made of similar material, exceptionally low bearing friction results, thereby insuring free rotation of the stirrer bar 30.

The stirrer bar 30, in the preferred form, includes an elongated mass 48 of magnetic material, encapsulated in chemically inert plastic polymeric material such as the above-mentioned TEFLON. The encapsulating material is designated by the reference numeral 50 in FIGS. 2 and 3.

Referring again to FIG. I, the apparatus is seen ready for use in a vessel 12. The shaft 24 is in gastight sealing relation with the central bore of stopper 18. The rotor assembly 26 is submerged within a medium 52, which may be for example a tissue culture medium.

The vessel 12 rests on a magnetic stirrer drive unit 54 of conventional construction. Thus, the drive unit 54 includes a motor 56, driving a magnet 58. Rotation of the magnet 58 causes like rotation of the stirrer bar and rotor assembly 26 to stir the medium 52.

As is seen in phantom line in FIG. 1, the height of the rotor assembly 26 within the vessel 12 is readily adjustable. Such adjustment may be accomplished simply by moving the shaft 24 axially with respect to the central bore 20. Such adjustment, it will be appreciated, may be made to adapt the magnetic stirrer 10 for use in vessels larger or smaller than the vessel 12.

Referring now to FIG. 4, there is seen a modified form of magnetic stirrer apparatus, designated generally by the reference numeral 10', wherein elements corresponding to those previously described are designated by like primed numerals. The apparatus 10 is operatively disposed within a vessel 12', which includes a top opening 14' and pouring spout I6. The vessel 12' is provided with external threads 60 near its top opening 14'.

The stirrer bar 30 is shown positioned within the vessel 12'. The stirrer bar 30' is secured, by press-fitting or the like, in a transverse bore 62 in a generally cylindrical sleeve member 64. A shaft 24' threadedly engages the sleeve member 64 at one of its ends. The other end of the shaft 24 is provided with an enlarged end portion 36'.

In the form of the apparatus shown in FIG. 4, the top opening 14' of the vessel 12' is sealed by a closure designated generally by reference numeral 66. The closure 66 includes a threaded cap 68, adapted to engage the threads 60 on the vessel 12'. Also, the closure 66 includes a support portion 70 adapted to be supported on the periphery of the top opening [4. A hollow sleeve member 28 may be formed integral with the support portion 70, is that it depends downwardly therefrom to project into the vessel 12' when the closure 66 is operatively disposed.

The sleeve member 28', like the above-described sleeve member 28, is provided with a major bore, designated by the numeral 32' and a minor bore 34' coaxial with the major bore 32'. The enlarged end portion 36' and shoulder 38 thus provide a bearing means, rotatably coupling the stirrer bar 30 to the closure 66. Hence, bearing surface 37' is downwardly facing while bearing surface 38' is upwardly facing.

Referring now to FIG. 5, there is seen an alternative means whereby the height of the stirrer bar 30, 30' may be adjusted within the vessels l2, 12.

A shaft, designated generally by the reference numeral 24", includes upper and lower portions 72, 74, respectively. The

construction of the shaft portions 72 and 74 is similar to that of the shaft 24. Thus, the upper and lower portions 72, 74 may include a coating 46 of chemically inert material such as the above-mentioned TEFLON." A sleeve 76 of chemically inert material such as TEFLON" joins the upper and lower portions 72, 74. The upper and lower portions 72, 74 are forcefitted into the sleeve 76. The de ree of telesco ing between the sleeve 76 and the upper and ower portions 2, 74 determines the overall length of the shaft 24", and consequently, the height of the stirrer bar associated with the shaft 24".

It should be understood that the above-described arrangement of the shaft 24"may be used, if desired, with either of the above-described embodiments l0, 10' of the apparatus.

The present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof.

I claim:

1. A magnetic stirrer apparatus for use with a nonmagnetic vessel having a gastight closure with an aperture therein connecting the interior of said vessel with the exterior comprising a stirrer bar, said stirrer bar being comprised of material that is responsive to magnetic forces, a sleeve, said sleeve supporting said stirrer bar and having an upper portion and a lower portion, elongated means, one end of said elongated means being coupled to the upper portion of said sleeve for relative rotation therebetween, the other end of said elongated means being substantially the same size as the aperture to extend therethrough in frictional sliding relation to the closure so that the aperture will be sealed when said stirrer bar is adjacent the bottom of the vessel.

2. A magnetic stirrer apparatus as defined in claim 1 wherein said sleeve is an elongated hollow member having at least two axially aligned bores of different diameters that define a downwardly facing bearing surface, said one end of said elongated means defining an upwardly facing bearing surface, and said elongated means is slidably received by said aligned bores and said bearing surfaces are in sliding rotational contact with each other.

3. A magnetic stirrer apparatus as defined in claim 2 including a transversely extending bore in said lower portion of said sleeve, and said stirrer bar being received in said opening.

4. Magnetic stirrer apparatus for use with a sealed nonmagnetic vessel comprising closure means positioned across an opening in said vessel to make a gastight seal, a downwardly depending hollow member having at least two axially aligned bores depending from said closure means, said bores defining an upwardly facing bearing surface, elongated means having one end receivable in said larger bore, said end defining a downwardly facing bearing surface, said bearing surfaces being in sliding rotational contact with each other to permit relative rotation between the vessel and said elongated means, a stirrer bar coupled in transverse relation to said elongated means for movement therewith.

5. Magnetic stirrer apparatus comprising a sleeve, said sleeve being a hollow elongated member having at least two axially aligned bores of different diameters that define a downwardly facing bearing surface, an elongated means, said elongated means having an enlarged portion defining an upwardly facing bearing surface at one end thereof, said elongated means and said enlarged portion being axially slidably received in said bores so that said bearing surfaces are in sliding rotational contact with each other, a portion of said sleeve having a transverse bore disposed below said enlarged portion, and a stirrer bar disposed in said transverse bore to limit said axially sliding between said sleeve and said elongated member. 

1. A magnetic stirrer apparatus for use with a nonmagnetic vessel having a gastight closure with an aperture therein connecting the interior of said vessel with the exterior comprising a stirrer bar, said stirrer bar being comprised of material that is responsive to magnetic forces, a sleeve, said sleeve supporting said stirrer bar and having an upper portion and a lower portion, elongated means, one end of said elongated means being coupled to the upper portion of said sleeve for relative rotation therebetween, the other end of said elongated means being substantially the same size as the aperture to extend therethrough in frictional sliding relation to the closure so that the aperture will be sealed when said stirrer bar is adjacent the bottom of the vessel.
 2. A magnetic stirrer apparatus as defined in claim 1 wherein said sleeve is an elongated hollow member having at least two axially aligned bores of different diameters that define a downwardly facing bearing surface, said one end of said elongated means defining an upwardly facing bearing surface, and said elongated means is slidably received by said aligned bores and said bearing surfaces are in sliding rotational contact with each other.
 3. A magnetic stirrer apparatus as defined in claim 2 including a transversely extending bore in said lower portion of said sleeve, and said stirrer bar being receivEd in said opening.
 4. Magnetic stirrer apparatus for use with a sealed nonmagnetic vessel comprising closure means positioned across an opening in said vessel to make a gastight seal, a downwardly depending hollow member having at least two axially aligned bores depending from said closure means, said bores defining an upwardly facing bearing surface, elongated means having one end receivable in said larger bore, said end defining a downwardly facing bearing surface, said bearing surfaces being in sliding rotational contact with each other to permit relative rotation between the vessel and said elongated means, a stirrer bar coupled in transverse relation to said elongated means for movement therewith.
 5. Magnetic stirrer apparatus comprising a sleeve, said sleeve being a hollow elongated member having at least two axially aligned bores of different diameters that define a downwardly facing bearing surface, an elongated means, said elongated means having an enlarged portion defining an upwardly facing bearing surface at one end thereof, said elongated means and said enlarged portion being axially slidably received in said bores so that said bearing surfaces are in sliding rotational contact with each other, a portion of said sleeve having a transverse bore disposed below said enlarged portion, and a stirrer bar disposed in said transverse bore to limit said axially sliding between said sleeve and said elongated member. 